Blasting machine



May 30, 1939. 2 M. D. MCCARTY BLASTING MACHINE Filed Feb. 1, 1938 22 m 04.244) W. M

Gnome Patented May 30, 1939 UNITED STATES PATENT oFFics BLASTING MACHINE poration of New York Application February 1, 1938, Serial No. 188,048

2 Claims. (on. 1-11-16) This invention relates generally to blasting machines, and more particularly to means for locking the machine in inoperative position when not in use, and safety means for breaking the 5 electrical circuit when the machine is in the inoperative position.

In seismograph work, unlike normal blasting; there of necessity must be a number of men near the blasting machine because of the many opera- 10 tions that are necessary in preparing a charge of explosive for the purpose of generating seismicwaves. When a number of men are engaged in preparingthe explosive charge, the handling of the explosive becomesmore hazardous. Thisis ll evidenced by the number of major accidents which have occurred in recent years in this. particular industry. 'A' number of these accidents have-been traced directly to a member of the party having carelessly prematurely introduced go an electric current into the blasting circuit.

Therefore-it is the primary object of this invention to provide means which may be used with v the conventional blasting machine for locking the machine in inoperative position so that it will 5 be necessary to insert a key in the lock and turn it before the plunger, which drives the generator, can be raised. Another object of this invention is in the provision of common means for both locking the go plunger of the machine and breaking the blasting circuit. v

Other objects and advantages of this inventionbeoome apparent from the following detailed description, when considered with the attached as drawing, in which: Y

Figure 1 is an elevationalview of a blasting machine shown partly in section, showing the improvements forming the subject tterof this v application in detail; 9 Figure 2 is a vertical sectional si e view of the blasting machine showing its elements; and

Figure 3 is the electrical circuit 0! the blasting machine shown diagrammatically. Referring to the drawing in detail, a blasting 4; machine of the plunger or generator type, comprising'a plimger I having arack gear 2 formed thereon adapted to drive a pinion 3 that is made integrally or attached to the gear 4. Gear I is adapted to drive the pinion 5 that is secured by so a key or othersuitable means tor/a shaft 8 of the generator 'I. With the gear train thus described, the armaturedof the generator can be driven at a. speed suiiiciently great that it will generate a voltageof the desired value that is 55 for detonating electric blasting caps.

As shown by the electric circuit illustrated in Figure 3, the generator 1 is connected in series with a switch 8 which is adapted to be closed by the bottom end of the plunger I just before it reaches its lowest position in the stroke. Additionally connected in series with the generator switch 8 and cap circuit, is a second switch 0 adapted to be actuated by a locking member it. The locking member I0 is of the conventional plunger type, having its plunger biased to the outward position by a spring II. The end I! of the plunger i is beveled in a manner commonly seen in ordinary door locks, and is adaptedto slide freely along the plunger I. The lock is so "be made integrally with the outer portion of the key ll. The cap it is provided with a hexagonally shaped flange whereby it may be gripped to turn the key in the lock. Obviously instead of providing the cap vwith the hexagonally shaped flange, it can be knurled or provided with an undulated periphery for the necessary hand hold.

Using a lock of this character in combination with the plunger as described, it is impossible to raise the plunger of the blasting machine until the key has been inserted in the lock and turned to retract the bolt.

As an additional safety feature in this blasting machine, there is. made integrally with the bolt of the lock III, a shaft or operating rod I which extends along the longitudinal axis of the bolt outwardly from the back end of the lock housing, and is adapted to carry on the outer end thereof a contactor II. when the bolt is retracted from the notch it in the plunger,'the contactor I1 is caused to engage another contactor secured to the case of the blastingma chine. l'hese two electrical contactor-s, when connected in the electrical circuit as shown, serve to open the blasting circuit or cap circuit of the machine and retain it in open relationship while the plunger is locked in inoperative position. In order to insure perfect contact between these two contactors, one or both of them may be made ,adjustable relative to the other.

Althoughthereisshownaspeciilcmeansf making and breaking the electrical circuit by the actuation of the bolt in the lock [0, it is obvious that many other typesof circuit making and breaking devices can be used and so arranged that their operation is dependent upon the movement of the bolt in the lock. 10.

I claim:

1. In a portable electrical generator type blastlng machine for detonating explosives for purposes of seismic surveys having a casing, a manually actuated plunger extending within said cas-o ing and an electrical generator positioned within the casing geared to the plunger and adapted to be actuated by the downward movement thereof, key releasable locking means within said casing for engaging the plunger to retain it in its inoperative position at the end of its downward movement, a switch within said casing, means for closing said switch shortly before said plunger reaches the end of its downward movement, a second switch in series with said first mentioned switch, and means connected to said locking means for opening said second switch when the locking means locks the plunger in inoperative position at the end of its downward movement, said plunger also extending through the casing v operative position.

wall and outwardly therefrom to a point beyond a the key releasable locking means and being adapted to function as a handle for carrying the machine when the plunger is secured in its locked, inoperative position. Y

2. In a portable electrical generator type blasting machine for detonating explosives for purposes of seismic surveys having a casing, a manually actuated plunger extending within said casing and an electrical generatorpositioned within the casing geared to the plunger and adapted to be actuated by the downward movement thereof, key releasable locking means within said casing for engaging the plunger to retain it in its inoperative position at the end of its downward movement, a, switch within said casing, means for closing said switch shortly before said plunger reaches the end of its downward movement, said plunger also extending through the casing wall and outwardly therefrom to a point beyond the key releasable locking means and being adapted to function as a handle for carrying the machine when the plunger is secured in its locked, in-

MALCOLM D. MCCARTY. 

